Polymers based on aliphatic diols and in particular isosorbides are of great interest to the chemical industry. Isosorbides are derived from biologically based sources, namely sugars, rather than from the petroleum feed stocks used to prepare other polymer structural units. Isosorbide-based materials and products are biodegradable, have a low net environmental impact, and can be utilized as renewable resources by the plastic manufacturing industry. These materials and products can be used for the production of polymeric materials such as polycarbonates. Polycarbonates are used in hundreds of applications such as eyeglass lenses and optical media, where their transparency and tough physical properties are beneficial.
According to the following reaction scheme, isosorbide can be made from biomass derived from starch through hydrolysis, hydrogenation, and dehydration reactions.

The efficient production of polycarbonates generally involves a number of trade-offs. For example, one can compensate for low reactivity of monomers by increasing catalyst concentration, time or temperature, but generally each such measure that one takes to make reaction conditions more aggressive involves a penalty in terms of increasing the yellowness of the transparent material.
Accordingly, there is a clear need for an efficient polymerization process to produce isosorbide-based polycarbonates having desirable color properties (i.e. low yellowness) and acceptably high molecular weight for commercial application.